Currently, the standardization of a wireless communication system of 4G is under way in 3GPP (Third Generation Partnership Project). According to 4G, improvements in maximum communication speed and quality improvements in cell edges can be realized by using technologies such as the relay and carrier aggregation. In addition, improvements of coverage are discussed by introducing base stations other than eNodeB (micro-cell base station) such as HeNodeB (Home eNodeB, femto-cell base station, small base station for mobile phones) and RHH (remote radio head). A relay apparatus (relay node) performing a relay is described in, for example, Patent Literature below.
In 3GPP, on the other hand, discussions about MTC (Machine Type Communications) are also under way. MTC is generally synonymous with M2M (Machine to Machine) and means communication between machines that is not directly used by humans. MTC is mainly performed between a server and an MTC terminal not directly used by humans.
As an MTC application in a medical system, for example, a case in which an MTC terminal collects electrocardiogram information of humans and transmits the electrocardiogram information to a server by using an uplink when some trigger condition is satisfied can be considered. As another MTC application, a case in which a vending machine is caused to function as an MTC terminal and a server causes vending machines under control to report sales at regular intervals (for example, 30 days) can also be considered.
Such an MTC terminal generally has, as an example, the following features, but each MTC terminal does not have to have all the following features and which features each MTC terminal has depends on the application.
Almost no movement (Low Mobility)
Small-capacity data transmission (Online Small Data Transmission)
Extremely low power consumption (Extra Low Power Consumption)
Handling by grouping MTC (Group based MTC Features)